From: Paolo Bonzini <pbonzini@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
ltt-dev@lists.casi.polymtl.ca, rp@svcs.cs.pdx.edu,
Darren Hart <darren@dvhart.com>, Ingo Molnar <mingo@elte.hu>,
tglx@linutronix.de, Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 0/7] priority-boost urcu
Date: Mon, 22 Aug 2011 11:10:35 +0200 [thread overview]
Message-ID: <4E521D0B.7030000@redhat.com> (raw)
In-Reply-To: <1313674225.15704.68.camel@gandalf.stny.rr.com>
On 08/18/2011 03:30 PM, Steven Rostedt wrote:
>> In QEMU I added the manual-reset event and use it in the
>> implementation of RCU.
That was me. :)
> Be careful with this. You better make sure that Microsoft does not hold
> any patents to this method, otherwise all your work will be in vain.
I found the synchronization primitive mentioned in a patent filed 1994,
so I would be surprised if the primitive itself is younger than 20 years
(or even younger than 30 years in fact).
The only possibly novel thing is the userspace-only path when there is
no contention. Windows events always do a system call, so there is some
hope it isn't patented.
But if Microsoft did have a patent and it applied, both the
userspace-RCU and QEMU code would have a problem. The technique is the
same independent of whether you call futex primitives directly, or you
wrap them in an API.
Paolo
prev parent reply other threads:[~2011-08-22 9:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1313478311.git.laijs@cn.fujitsu.com>
[not found] ` <4E4B7FEB.6050200@redhat.com>
[not found] ` <4E4C971D.9020902@cn.fujitsu.com>
2011-08-18 12:28 ` [RFC PATCH 0/7] priority-boost urcu Mathieu Desnoyers
2011-08-18 13:30 ` Steven Rostedt
2011-08-22 9:10 ` Paolo Bonzini [this message]
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